In a typical virtual machine environment, multiple virtual machines or “partitions” run on top of virtualizing software. This software, in turn, runs on top of hardware. The virtualizing software exposes the hardware in such a fashion that allows for a plurality of partitions, each with its own operating system (OS), to run on the hardware. The hardware is thus virtualized for the partitions by the virtualizing software.
Individual partitions are able to run disparate OSes, such as Windows, Linux, Solaris, and so on. These OSes can be isolated from each other such that if one OS in a partition crashes it will not affect other OSes in other partitions.
One cost associated with running multiple partitions on one set of hardware is that the virtualizing software consumes significant processor cycles as it virtualizes devices for each partition. Likewise, the virtualizing software consumes significant cycles as information (requests and/or data) or devices are shared among such partitions, the reason being that the virtualizing software must process this information and devices as it is being shared across partitions.
Specifically, in any given virtual machine environment, a class of problems arises because some, and probably all, of the input/output devices present in the partitions have not been designed to be shared with multiple OSes found in other partitions. Most devices' programming models assume that there is one and only one OS that “owns” the device, which makes it very hard or impossible to use that device simultaneously by several operating systems found in various partitions. Problems could arise if, for example, a disk controller were getting commands simultaneously from two operating systems. Each would think that it controlled the file system structures, and each would write whatever data it chose and soon the disk would be corrupted. To keep this from happening, it would be advantageous to devise some method and system to assign ownership of a device to a single operating system and then share that device's services with any other running operating system.
Additionally, a separate class of problems arises when multiple operating systems try to share the same machine, because users need some level of integration between these operating systems. For example, a user may want to move data between the operating systems found in their respective partitions. Thus, it would also be advantageous to provide a method and system of moving data, or more broadly, information between running operating systems.